Allison 3000 & 4000 Gen 4 Fault Code: P0604 Internal Control Module Random Access Memory (RAM) Error
DIAGNOSTIC RESPONSE: Use default sump temperature
CIRCUIT DESCRIPTION: The Transmission Control Module (TCM) performs an internal memory self-test at power up that writes and reads patterns at specific RAM locations to verify that all addresses and data lines are functioning correctly.
CONDITIONS FOR RUNNING THE DTC: TCM software level January 2011 or higher.
CONDITIONS FOR SETTING THE DTC: DTC P0604 sets if the TCM determines the TCM memory pattern that was written is not what was read from TCM memory during the self- test.
ACTION TAKEN WHEN THE DTC SETS: 1. The CHECK TRANS light illuminates. 2. DTC is stored in the TCM history on next key cycle. 3. All-segments symbol illuminates in both shift selector displays. 4. The TCM returns to the boot program. 5. The TCM inhibits shifts to range.